The present invention relates generally to anti-theft detection systems, and more particularly to an anti-theft electronic security system using a frequency multiplier.
Electronic security systems are known for the detection of unauthorized removal of items from stores and other facilities. These detection systems are beneficial in that the presence of such detection systems deters shoplifting theft and allows for the apprehension of those not deterred. These detection systems are found in a variety of locations, including retail stores, particularly those selling clothing, books, videotapes, and the like. The detection system sometimes comprises a magnetic strip attached to a good along with a detector which monitors magnetic fields for determining when the magnetic strip passes through an area proximate the detector. The detection system sometimes also comprises plastic tags attached to clothing and the like, also along with a magnetic field detector. The plastic tags contain a resonant circuit which, when passed through a magnetic field, resonate and disrupt the magnetic field in a detectable manner. Detection systems of this type have been installed in a large number of locations, and are widely used.
These detection systems are not without problems, however. The magnetic strip or tag containing a resonant circuit, both of which may be generally described as a target, is generally attached (and sometimes detached) by a retailer in a labor intensive operation. The targets also are often too large to be accommodated easily by many retail items, or too expensive to justify using with certain items, particularly those found in retail food and drug stores. These detection systems also do not allow for the placement of goods near the detectors as such goods would activate the sensing alarm. This decreases the amount of floor space available for the display of product. These detection systems also are adversely affected by the presence of nearby metallic objects, as well as by noise generators such as laser product scanners and the like. Additionally, there is evidence that some detection systems affect pacemaker operations, and therefore possibly pose health risks to individuals who require the use of a pacemaker.